<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <script src="./jq-3.6.0.js"></script>
    <style>
        .big {
            height: 200px;
            width: 200px;
            background-color: red;
        }
        
        .small {
            height: 50px;
            width: 50px;
            background-color: green;
        }
    </style>
</head>

<body>
    <button>1</button>
    <div class="big">
        <div class="small"></div>
    </div>
</body>
<script>
    $('button').on('click', function(event) {
        console.log(11111111);
        return event.preventDefault();
        // return false;
        console.log(2222222);
    })

    $('.big').on('click', function(event) {
        console.log(333333);
    })
    $('.small').on('click', function(event) {
        console.log(444444);
        // event.stopPropagation();

    })
    setTimeout(function() {
        $('.small').triggerHandler('click');
    }, 2000)
</script>

</html>